Synthetic foams have been widely used as packing material; in mattresses and pet bedding; as cushioning in furniture, automobiles, and boats; in shoes and padded costumes; in the construction and building materials industries; and for a variety of biomedical applications. Polyurethanes are polymeric compositions that are commonly used in foam applications; polyurethanes are formed through the reaction of one or more polyfunctional alcohols with polyisocyanates. Foam formation occurs when a gas or low boiling point liquid is introduced to the reaction mixture during the polymerization process.
However, polyurethanes have many drawbacks. The raw materials for their synthesis are often hydrocarbon based and ultimately derived from petroleum, and synthesis is often carried out in organic solvents, which are expensive and difficult to dispose of, as well as potentially hazardous for the environment. Additionally, many polyurethanes are not biodegradable. Further, attempts to introduce natural polyols into polyurethane compositions have been limited, often due to the rarity and/or cost of the natural materials, or to their non-ideal physical and chemical characteristics. Finally, many polyurethane foams are not resistant to chemical exposure, such as exposure to acids, and many polyurethane foams are slow, or simply unable, to return to their original shapes and/or sizes after pressure has been applied.
It would thus be desirable to develop a polyurethane composition that is suitable for producing foams and that is based on inexpensive, readily-available natural products. Ideally, the synthesis of such a polyurethane would not require the use of organic solvents and the resulting foam would possess desirable properties such as acid resistance, heat resistance, and recovery of its original shape and size after the application of pressure.